Thruster aided steering system

Abstract

A vessel with auxiliary steering includes a vessel hull with a bow/stern centerline and a port and starboard side. The vessel has (i) a main propulsion unit including at least one propeller and at least one main rudder, and (ii) a secondary propulsion unit including at least one directional water jet thruster on each of the port and starboard side of the vessel hull. The water jet thrusters are configured to direct water outwardly and perpendicularly to the centerline of the hull, and a control system coordinates the direction of the main rudder and the flow direction of at least one water jet thruster.

The invention claimed is: 
     
       1. A vessel with auxiliary steering comprising;
 a. a vessel hull with a bow/stern centerline and a port and starboard side; 
 b. a main propulsion unit including at least one propeller and at least one main rudder; 
 c. a secondary propulsion unit including at least one directional water jet thruster on each of the port and starboard side of the vessel hull, the water jet thrusters including a plurality of adjustable rudders to control the flow direction of the water; 
 d. wherein the water jet thrusters are configured to direct water outwardly and perpendicularly to the centerline of the hull; and 
 e. a control system coordinating a position of the main rudder to a position of the water jet thruster rudders of at least one water jet thruster. 
 
     
     
       2. The vessel of  claim 1 , wherein the water jet thrusters are positioned at an approximate pivot point of the vessel. 
     
     
       3. The vessel of  claim 2 , wherein the pivot point is located approximately ⅔rd a length of the hull from a stern of the hull. 
     
     
       4. The vessel of  claim 1 , wherein the control system is configured to adjust the starboard water jet thruster flow direction in conjunction with port main rudder direction. 
     
     
       5. The vessel of  claim 1 , wherein the control system is configured to adjust the port water jet thruster in conjunction with a starboard main rudder direction. 
     
     
       6. The vessel of  claim 1 , wherein a ratio of a position change of the main rudder to a position change of the water jet thruster rudders is between 1:1.5 and 1:2.5. 
     
     
       7. The vessel of  claim 1 , wherein a ratio of a position change of the main rudder to a position change of the water jet thruster rudders is about 1:2. 
     
     
       8. A vessel with auxiliary steering comprising;
 a. a vessel hull with a bow/stern centerline and a port and starboard side; 
 b. a main propulsion unit including at least one propeller and at least one main rudder; 
 c. a secondary propulsion unit including at least one directional water jet thruster on each of the port and starboard side of the vessel hull, the water jet thrusters including a plurality of adjustable rudders to control the flow direction of the water; 
 d. a control system configured to coordinate the position of the thruster rudders of the water jet thruster on the vessel side opposing a direction of the main rudder. 
 
     
     
       9. The vessel of  claim 8 , wherein a ratio of a position change of the main rudder to a position change of the water jet thruster rudders is between 1:1.5 and 1:2.5. 
     
     
       10. The vessel of  claim 8 , wherein a double acting piston acts to adjust a position of the thruster rudders. 
     
     
       11. The vessel of  claim 8 , wherein the secondary propulsion unit includes a flow divider capable of adjusting relative flow between the port and starboard water jet thrusters. 
     
     
       12. The vessel of  claim 8 , wherein the thruster rudders are positioned within an inset on the hull such that the thruster rudders have at least one position not extending beyond a side plane of the hull. 
     
     
       13. The vessel of  claim 8 , wherein the power of the secondary propulsion unit is between about 15% and about 30% of the main propulsion unit. 
     
     
       14. The vessel of  claim 13 , wherein the main propulsion unit is between 200 and 15,000 horsepower. 
     
     
       15. A method of operating a vessel wherein the vessel comprises (i) a main propulsion unit including at least one propeller and at least one main rudder, (ii) a secondary propulsion unit including at least one directional water jet thruster on each of the port and starboard side of the vessel hull, the water jet thrusters including a plurality of adjustable rudders to control the flow direction of the water;
 and (iii) a control system coordinating a position of the main rudder to a position of the water jet thruster rudders to control a flow direction of the water jet thrusters, the method comprising the steps of: 
 a. operating the main propulsion unit to impart a forward speed to the vessel of at least five knots; and 
 b. operating the water jet thrusters to direct thrust predominantly toward the stern of the vessel. 
 
     
     
       16. The method of  claim 15 , wherein the water jet thrusters direct thrust between 10° and 35° of a bow/stern centerline of the vessel. 
     
     
       17. The method of  claim 15 , further comprising the steps of subsequently applying left rudder and changing the direction of thrust of the starboard water jet thruster to a greater angle with respect to a bow/stern centerline of the vessel. 
     
     
       18. The method of  claim 17 , wherein the change in direction of thrust of the starboard water jet thruster is approximately twice the change in left rudder.